Stromal vascular fraction: Mechanisms and application in reproductive disorders

Figure 1 Summary of components, mechanisms, and application of stromal vascular fraction in reproductive therapy. Stromal vascular fraction (SVF) contains adipose-derived stem cells, pericytes, endothelial progenitor cells, and immune cells. It has an immunomodulatory function, and proangiogenic effect, and contributes to tissue repair and regeneration. For immunomodulatory functions, SVF can directly modulate both innate and adaptive immune cell functions. It can also suppress pro-inflammatory cytokines and regulate immune tolerance via cell-cell interaction and secretory molecules. For proangiogenic effect, endothelial progenitor cells, pericytes, and macrophages cooperate to secrete pro-angiogenic factors, differentiate into cells that structure new blood vessels, and contribute to vessel stabilization. For tissue repair and regeneration, SVF can either differentiate into repair cells or attract progenitor cells to differentiate into target cells via trophic factors secretion. Fibroblasts in SVF can remodel the extracellular matrix by secreting collagen and metalloproteinase. In male reproductive disorders, SVF has the potential to be applied to the treatment of erectile dysfunction and testicular injury. In female reproductive disorders, SVF has the potential to be applied to the treatment of intrauterine adhesion and stress urinary incontinence. SVF: Stromal vascular fraction; Treg: Regulatory T; IL: Interleukin; TGF: Transforming growth factor; TNF: Tumour necrosis factor; PD-1: Programmed cell death protein-1; PD-L1: Programmed death-ligand 1; HLA: Human leukocyte antigen; PGE2: Prostaglandin E2; HGF: Hepatic growth factor; NK: Natural killer; PDGF: Platelet-derived growth factor; VEGF: Vascular endothelial growth factor; ECM: Extracellular matrix; NF-κB: Nuclear factor-kappaB.